In China, authorities began charging higher duties on American imports at midday Sunday, according to employees who answered the phone at customs offices in Beijing and the southern port of Guangzhou. They declined to give their names.

Tariffs of 10 and five per cent apply to items ranging from frozen sweet corn and pork liver to marble and bicycle tires, the government announced earlier.

After Sunday's move, 87 per cent of textiles and clothing the United States buys from China and 52 per cent of shoes will be subject to import taxes.

On Dec. 15, the Trump administration is scheduled to impose a second round of 15 per cent tariffs — this time on roughly $160 billion of imports. If those duties take effect, virtually all goods imported from China will be covered.

The Chinese government has released a list of American imports targeted for penalties on Dec. 15 if the U.S. tariff hikes take effect. In total, Beijing says Sunday's penalties and the planned December increases will apply to $75 billion of American goods.

U.S. accuses China of stealing trade secrets

Washington and Beijing are locked in a war over U.S. complaints that China steals U.S. trade secrets and unfairly subsidizes its own companies in its drive to develop global competitors in such high-tech industries as artificial intelligence and electric cars.

"I give the president credit for challenging China on some of its really egregious behaviour" on intellectual property and technology transfers, for example, Toomey said. He said he hopes that's what Trump's focus is, "not just the fact that Chinese clothing and shoes are popular among consumers. That's not the problem."

If China changes its behaviour "in a meaningful way in that area ... then we will have ended up in a better place. That's what I'm hoping for. But let's be honest. In the meantime, we're doing damage. It's a double-edged sword," he said.

To try to force Beijing to reform its trade practices, the Trump administration has imposed import taxes on billions of dollars' worth of Chinese imports, and China has retaliated with tariffs on U.S. exports.

"It's a good thing taking on China. Unfortunately, he's done it the wrong way," said American Federation of Labour and Congress of Industrial Organizations president Richard Trumka said on "Fox News Sunday."

"To take on China there has to be a multilateral approach. One country can't take on China to try to dry up its overcapacity because they just send it through to you in other ways," he said.

Trump has insisted that China itself pays the tariffs. But in fact, economic research has concluded that the costs of the duties fall on U.S. businesses and consumers. Trump had indirectly acknowledged the tariffs' impact by delaying some of the duties until Dec. 15, after holiday goods are already on store shelves.

'Erosion of consumer confidence'

A study by J.P. Morgan found that Trump's tariffs will cost the average U.S. household $1,000 a year. That study was done before Trump raised the Sept. 1 and Dec. 15 tariffs to 15 from 10 per cent.

The president has also announced that existing 25 per cent tariffs on a separate group of $250 billion of Chinese imports will increase to 30 per cent on Oct. 1.

That cost could weaken an already slowing U.S. economy. Though consumer spending grew last quarter at its fastest pace in five years, the overall economy expanded at just a modest two per cent annual rate, down from a 3.1 per cent rate in the first three months of the year.

The economy is widely expected to slow further in the months ahead as income growth slows, businesses delay expansions and higher prices from tariffs depress consumer spending. Companies have already reduced investment spending, and exports have dropped against a backdrop of slower global growth.
Americans have already turned more pessimistic. The University of Michigan's consumer sentiment index, released Friday, fell by the most since December 2012.

"The data indicate that the erosion of consumer confidence due to tariff policies is now well underway," said Richard Curtin, who oversees the index.

Some retailers may eat the cost of the tariffs. Target confirmed to The Associated Press that it warned suppliers that it won't accept cost increases arising from the China tariffs. But many smaller retailers won't have the bargaining power to make such demands and will pass the costs to customers.

Philip Levy, chief economist at the San Francisco freight company Flexport who was an adviser in President George W. Bush administration, said it's hard to say for sure when the latest tariffs may hit U.S. customers in the form of higher prices.

But, he added, "If you had to pick a time to do it, this is the worst possible time" because it's when the bulk of holiday goods are brought into the country.